BIO130Chapter14Notes

BIO130Chapter14Notes - Nervous System: Brain and Cranial...

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Unformatted text preview: Nervous System: Brain and Cranial Nerves (Chapter 14) The Brain and Cranial Nerves Spinal cord ! reflex = immediate response Brain ! thinking = adaptable but slower Lecture Materials for Amy Warenda Czura, Ph.D. Suffolk County Community College Eastern Campus Brain Structure 1. Cerebrum -largest part of human brain -2 cerebral hemispheres covered in cerebral (neural) cortex -surface convoluted to increase surface area for neurons (~3ft2) -gyri = elevated ridges -sulci = depressions -fissures = big sulci P r im a r y S o u r c e s f o r fi g u r e s a n d c o n te n t: Marieb, E. N. Human Anatomy & Physiology 6th ed. San Francisco: Pearson Benjamin C u m m in g s , 2 0 0 4 . M a r tin i, F . H . F u n d a m e n ta ls o f A n a to m y & P h y s io lo g y 6 th e d . S a n F r a n c is c o : P e a r s o n B e n ja m in C u m m in g s , 2 0 0 4 . -central sulcus divides frontal lobes from parietal lobes -lateral sulcus divides frontal lobes from temporal lobes -parieto-occipital sulcus divides parietal lobes from occipital lobes -insula located at base of lateral sulcus beneath frontal and temporal lobes -longitudinal fissure separates left and right hemispheres -base of fissure has corpus callosum: axons to connect neurons of hemispheres -hemispheres divided into five lobes each Amy Warenda Czura, Ph.D. 1 SCCC BIO130 Chapter 14 Lecture Notes 2. Cerebellum -second largest part -consists of right and left hemispheres connected by the vermis -covered in cerebellar cortex -folia instead of gyri -each hemisphere divided into anterior and posterior lobes by the primary fissure 3. Diencephalon -links cerebral hemispheres to brain stem -3 parts: epithalamus, thalamus, hypothalamus 4. Brain stem -connects to spinal cord -consists of mesencephalon, pons, and medulla oblongata 5. Ventricles -holes in brain that circulate CSF A. Lateral ventricles -in each cerebral hemisphere B. Third ventricle -in diencephalon C. Fourth ventricle -in between pons and cerebellum -connects to central canal of spinal cord 2. Cranial meninges -hold brain in place -prevent contact with skull A. Dura mater -two layers -no epidural space: fused to periosteum -forms dural folds deep into fissures: 1. falx cerebri: between cerebral hemispheres in longitundinal fissure 2. tentorium cerebelli: between cerebrum and cerebellum 3. falx cerebelli: between cerebellar hemispheres Protection of the brain 1. Cranial bones: form the skull -occipital, frontal, sphenoid, ethmoid, parietals, temporals Amy Warenda Czura, Ph.D. 2 SCCC BIO130 Chapter 14 Lecture Notes -volume of CSF in brain and cord turned over every 8hrs -choroid plexus secretes ~500ml/day B. Arachnoid 1. arachnoid membrane 2. arachnoid trabeculae: span subarachnoid space which contains CSF C. Pia mater -adheres to brain via astrocytes -follows topology of gyri and sulci -CSF reabsorbed at arachnoid granulations 3. Cerebrospinal fluid -functions: a. cushion brain b. support brain c. diffusion medium -produced by choroid plexus (= ependymal cells plus capillaries in brain ventricles) Hydrocephalus = (infants) failure to reabsorb CSF, fluid expands cranium and crushes brain 4. Blood-brain barrier -capillaries of CNS less permeable: -endothelial cells linked by tight junctions -astrocytes cover capillary surface http://www.telegraph.co.uk/news/graphics/2005/04/28/wviet28a.jpg http://tier.cs.berkeley.edu/gallery/ghana05/IMGP1551_001 http://www.diagnostico.com/T rejos/HydrocephalusIII.JPG Amy Warenda Czura, Ph.D. -only lipid soluble compounds diffuse into CNS, all others actively transported by astrocytes -inflammation (infection, cancer) can break down blood brain barrier http://uuhsc.utah.edu/healthinfo/images/ei_0433.gif 3 SCCC BIO130 Chapter 14 Lecture Notes Brain Anatomy: (on handout) Brainstem 1. Medulla Oblongata (details on handout) 3. Midbrain / Mesencephalon (details on handout) Diencephalon (details on handout) 2. Pons (details on handout) Cerebellum (details on handout) -located between cerebrum and diencephalon: parts of both -functions: -establishes emotional states and drives -links conscious functions of cerebrum to autonomic functions of brainstem -facilitates memory storage and retrieval Special regions 1. amygdala: fight or flight, initiates fear response, links emotion with memory 2. hippocampus: memory and learning 3. cingulate gyrus: expressing emotions via gestures, & resolves mental conflicts Ataxia = loss of balance due to disruption in cerebellum (e.g. alcohol) Limbic System -functional not anatomical separation Amy Warenda Czura, Ph.D. 4 SCCC BIO130 Chapter 14 Lecture Notes Cerebrum (details on handout) Examples of integrative centers: 1. Wernicke’s area = general interpretive area -center of left hemisphere -gives meaning to auditory or visual cues 2. Broca’s area = speech center -left hemisphere superior to lateral sulcus -coordinates motor controls for speech 3. Prefrontal cortex -anterior frontal lobes -prediction, estimation, and related emotions Association and integration areas all over cortex carry out all levels of thought but in general: -Left hemisphere: language, math, logic -Right hemisphere: interpret sensory info, generate emotions, spatial visualization -each hemispheres sends info to opposite side of body but each also has unique functions -hemispheres communicate for whole thought -if corpus callosum cut, hemispheres work independently e.g. (used as treatment for seizures) Epileptic seizures = abnormal electrical activity in brain; causes loss of normal function Anencephaly = brain fails to develop above mesencephalon, fatal Cerebrovascular Accident (CVA) = “stroke”, loss of blood supply to brain, neuron death occurs in minutes *Individual cranial nerves and their innervations will be examined in detail in lab! Amy Warenda Czura, Ph.D. 5 SCCC BIO130 Chapter 14 Lecture Notes ...
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